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Groups > sci.electronics.design > #446173
| From | Don Y <blockedofcourse@foo.invalid> |
|---|---|
| Newsgroups | sci.electronics.design |
| Subject | Re: OT: in favour of gradualism |
| Date | 2017-02-04 15:46 -0700 |
| Organization | A noiseless patient Spider |
| Message-ID | <o75lgn$oa3$2@dont-email.me> (permalink) |
| References | (5 earlier) <efmqjcFe61gU1@mid.individual.net> <o75g67$6t9$1@dont-email.me> <tqjc9ct91aa4dopd9rvu2d96j16ss8loug@4ax.com> <o75ju9$jc7$1@dont-email.me> <o75ktq$mk7$1@dont-email.me> |
On 2/4/2017 3:36 PM, tom wrote: > "Don Y" <blockedofcourse@foo.invalid> wrote in message > news:o75ju9$jc7$1@dont-email.me... >> On 2/4/2017 3:02 PM, John Larkin wrote: >>>> You spec a 2000hr part in a power supply. It meets the design >>>> specifications. >>>> It meets the expected lifespan of the product (e.g., clears warranty). >>>> But, >>>> realistically, you KNOW that this will result in the $200 product being >>>> shit-canned in 2-3 years (of normal use). >>> >>> A typical aluminum electrolytic cap will have a rated lifetime of 2000 >>> hours, and a shelf life the same. That's 80 days, totally insane. Does >>> Digikey stock them for hours, like dougnnuts? They actually work for >>> decades. >> >> The hour rating on an ecap indicates lifetime to a particular loss of >> capacitance AT WVDC AND OPERATING TEMPERATURE. >> >> So, spec a 105C cap in a device that is operating at an ambient of 25C >> with virtually no self-heating from ripple current and it will degrade >> at a rate ~250 times slower than that exact same component operating >> at a combined ambient + self-heating temperature of 100C. >> >> E.g., in a power supply where ripple currents tend to be high AND >> ambient temperature elevated (because other nearby components are >> dissipating power) and you WILL notice a marked difference in >> lifetimes between 2000hr components and 5000hr devices. >> >> Given that the cost (labor) of repairing damn near anything makes >> a $100-200 item effectively disposable, then specing a 2000hr part >> when you could just as easily spec a 5000hr part (without incurring >> HUGE cost increases IN BIG VOLUME) is far from "perfection"... >> regardless of how well it fits the spec and cost targets! >> >> (think: externalities) > > Exactly. Think warranty timer. Conversely, for a few pennies more, you could produce a QUALITY product (though often depriving yourself of a REPLACEMENT SALE a couple of years down the road). [But, heck, you may not even be in business, then!]
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OT: in favour of gradualism bill.sloman@ieee.org - 2017-02-03 03:39 -0800
Re: OT: in favour of gradualism Winfield Hill <hill@rowland.harvard.edu> - 2017-02-03 04:21 -0800
Re: OT: in favour of gradualism bill.sloman@ieee.org - 2017-02-03 04:57 -0800
Re: OT: in favour of gradualism Jon Elson <elson@pico-systems.com> - 2017-02-03 11:38 -0600
Re: OT: in favour of gradualism Joerg <news@analogconsultants.com> - 2017-02-04 07:21 -0800
Re: OT: in favour of gradualism krw@notreal.com - 2017-02-04 10:42 -0500
Re: OT: in favour of gradualism Joerg <news@analogconsultants.com> - 2017-02-04 08:15 -0800
Re: OT: in favour of gradualism krw@notreal.com - 2017-02-04 11:36 -0500
Re: OT: in favour of gradualism Joerg <news@analogconsultants.com> - 2017-02-04 09:40 -0800
Re: OT: in favour of gradualism krw@notreal.com - 2017-02-04 13:52 -0500
Re: OT: in favour of gradualism Joerg <news@analogconsultants.com> - 2017-02-04 11:50 -0800
Re: OT: in favour of gradualism krw@notreal.com - 2017-02-04 20:31 -0500
Re: OT: in favour of gradualism Jon Elson <elson@pico-systems.com> - 2017-02-04 18:04 -0600
Re: OT: in favour of gradualism krw@notreal.com - 2017-02-04 20:33 -0500
Re: OT: in favour of gradualism jurb6006@gmail.com - 2017-02-03 05:00 -0800
Re: OT: in favour of gradualism bill.sloman@ieee.org - 2017-02-03 09:03 -0800
Re: OT: in favour of gradualism Don Y <blockedofcourse@foo.invalid> - 2017-02-03 09:35 -0700
Re: OT: in favour of gradualism bill.sloman@ieee.org - 2017-02-03 09:10 -0800
Re: OT: in favour of gradualism tabbypurr@gmail.com - 2017-02-03 17:18 -0800
Re: OT: in favour of gradualism Joerg <news@analogconsultants.com> - 2017-02-04 07:24 -0800
Re: OT: in favour of gradualism Don Y <blockedofcourse@foo.invalid> - 2017-02-04 12:34 -0700
Re: OT: in favour of gradualism tabbypurr@gmail.com - 2017-02-04 12:04 -0800
Re: OT: in favour of gradualism Joerg <news@analogconsultants.com> - 2017-02-04 12:07 -0800
Re: OT: in favour of gradualism Don Y <blockedofcourse@foo.invalid> - 2017-02-04 14:15 -0700
Re: OT: in favour of gradualism John Larkin <jjlarkin@highlandtechnology.com> - 2017-02-04 14:02 -0800
Re: OT: in favour of gradualism Don Y <blockedofcourse@foo.invalid> - 2017-02-04 15:19 -0700
Re: OT: in favour of gradualism "tom" <tmiller11147@verizon.net> - 2017-02-04 17:36 -0500
Re: OT: in favour of gradualism Don Y <blockedofcourse@foo.invalid> - 2017-02-04 15:46 -0700
Re: OT: in favour of gradualism Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-02-04 14:56 -0800
Re: OT: in favour of gradualism Don Y <blockedofcourse@foo.invalid> - 2017-02-04 16:17 -0700
Re: OT: in favour of gradualism "tom" <tmiller11147@verizon.net> - 2017-02-04 18:22 -0500
Re: OT: in favour of gradualism Don Y <blockedofcourse@foo.invalid> - 2017-02-04 16:55 -0700
Re: OT: in favour of gradualism John Robertson <spam@flippers.com> - 2017-02-04 18:22 -0800
Re: OT: in favour of gradualism Don Y <blockedofcourse@foo.invalid> - 2017-02-04 21:26 -0700
Re: OT: in favour of gradualism "tom" <tmiller11147@verizon.net> - 2017-02-04 17:35 -0500
Re: OT: in favour of gradualism Don Y <blockedofcourse@foo.invalid> - 2017-02-04 15:44 -0700
Re: OT: in favour of gradualism "dcaster@krl.org" <dcaster@krl.org> - 2017-02-04 17:42 -0800
Re: OT: in favour of gradualism krw@notreal.com - 2017-02-04 20:56 -0500
Re: OT: in favour of gradualism Joerg <news@analogconsultants.com> - 2017-02-05 08:14 -0800
Re: OT: in favour of gradualism Don Y <blockedofcourse@foo.invalid> - 2017-02-05 11:56 -0700
Re: OT: in favour of gradualism Joerg <news@analogconsultants.com> - 2017-02-06 14:35 -0800
Re: OT: in favour of gradualism Don Y <blockedofcourse@foo.invalid> - 2017-02-06 16:43 -0700
Re: OT: in favour of gradualism Joerg <news@analogconsultants.com> - 2017-02-06 17:12 -0800
Re: OT: in favour of gradualism Don Y <blockedofcourse@foo.invalid> - 2017-02-06 18:59 -0700
Re: OT: in favour of gradualism Joerg <news@analogconsultants.com> - 2017-02-07 07:40 -0800
Re: OT: in favour of gradualism tabbypurr@gmail.com - 2017-02-07 12:16 -0800
Re: OT: in favour of gradualism krw@notreal.com - 2017-02-06 21:11 -0500
Re: OT: in favour of gradualism tabbypurr@gmail.com - 2017-02-05 12:43 -0800
Re: OT: in favour of gradualism krw@notreal.com - 2017-02-04 20:42 -0500
Re: OT: in favour of gradualism John Larkin <jjlarkin@highlandtechnology.com> - 2017-02-04 10:05 -0800
Re: OT: in favour of gradualism Joerg <news@analogconsultants.com> - 2017-02-04 10:24 -0800
Re: OT: in favour of gradualism Don Y <blockedofcourse@foo.invalid> - 2017-02-04 12:45 -0700
Re: OT: in favour of gradualism "dcaster@krl.org" <dcaster@krl.org> - 2017-02-04 17:54 -0800
Re: OT: in favour of gradualism Don Y <blockedofcourse@foo.invalid> - 2017-02-04 21:45 -0700
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